diff --git a/test/var_append.mk b/test/var_append.mk
new file mode 100644
index 0000000..5519299
--- /dev/null
+++ b/test/var_append.mk
@@ -0,0 +1,17 @@
+# TODO
+S:=simple
+R=recursive
+
+foo=FOO
+bar=
+
+S+=$(foo) $(bar)
+R+=$(foo) $(bar)
+
+bar=BAR
+
+test:
+	echo "$(S)"
+	echo "$(R)"
+	echo "$(flavor S)"
+	echo "$(flavor R)"